1. Technical Field
The present invention relates in general to an improved disk drive, and in particular to an improved disk drive having a device for immobilizing the disk spindle. Still more particularly, the present invention relates to a membrane-like locking device for selectively immobilizing the disks and/or spindle in a disk drive device.
2. Description of the Prior Art
Generally, a data access and storage system consists of one or more storage devices that store data on storage media such as magnetic or optical data storage disks. In magnetic disk storage systems, a storage device is called a direct access storage device (DASD) or a hard disk drive (HDD), which includes one or more hard disks and an HDD controller to manage local operations concerning the disks. Hard disks are rigid platters, typically made of aluminum alloy or a mixture of glass and ceramic, covered with a magnetic coating. Typically, two or three platters are stacked vertically on a common spindle that is turned by a disk drive motor at several thousand revolutions per minute (rpm).
The only other moving part within a typical HDD is the head stack assembly. Within most drives, one read/write head is associated with each side of each platter and flies just above or below the platter""s surface. Each read/write head is mounted on a suspension to form a head gimbal assembly (HGA). The HGA is then attached to a semi-rigid arm apparatus which supports the entire head flying unit. More than one of such arms may be utilized together to form a single armature unit.
Each read/write head scans the hard disk platter surface during a xe2x80x9creadxe2x80x9d or xe2x80x9cwritexe2x80x9d operation. The head/arm assembly is moved utilizing an actuator which is often a voice coil motor (VCM). The stator of a VCM is mounted to a base plate or casting on which is also mounted the spindle supporting the disks. The base casting is in turn mounted to a frame via a compliant suspension. When current is fed to the motor, the VCM develops force or torque which is substantially proportional to the applied current. The arm acceleration is therefore substantially proportional to the magnitude of the current. As the read/write head nears the desired track, a reverse polarity signal is applied to the actuator, causing the signal to act as a brake, and ideally causing the read/write head to stop directly over the desired track.
Head-to-disk stiction in disk drives has proven to be more difficult to control as the head-to-disk spacing has decreased. Disk surfaces as well as head surfaces have become smoother to permit closer fly height. This has resulted in increased problems of heads sticking to disks when the drive is at rest. In addition, shock impact of both the head and suspension cause xe2x80x9cdingsxe2x80x9d or dents in the disks and have become more problematic due to several factors. For example, mobile applications, such as laptops, have increased the ambient shock impact of both the head and suspension cause xe2x80x9cdingsxe2x80x9d or dents in the disks and have become more problematic due to several factors. For example, mobile applications, such as laptops, have increased the ambient shock environment. Moreover, the decrease in disk-to-disk spacing has resulted in closer suspension-to-disk spacing, and higher areal densities have made drives more susceptible to even minor dings. In addition, more drives are being handled by untrained personnel in the high-volume marketplace.
To address these problems, future disk drives will have a ramp to unload the heads from the disk when the drive is at rest. Unfortunately, this solution has created a new potential problem. When the heads are at rest on the disk, the slight stiction they created stabilized any random rotation or vibration of the spindle as the drive was being transported. However, with no heads on the disks, the spindle is now free to rotate. Under these circumstances, the spindle ball bearings can experience slight vibratory motion as the drive is being transported. Since there is no continuous rolling of the balls on the races to replenish the lubrication, the lubrication can be forced out of the interface. Without lubrication, there is direct metal-to-metal contact which can cause fretting corrosion of both the races and the balls. This problem is manifested as localized pitting and release of oxide particles. When the bearing becomes operational, the free particles and localized pits can interact to degrade bearing performance. Such a breakdown is typically manifested by increased acoustic noise and non-repeatable run out also have drawbacks such as complexity, decreased reliability, and increased cost. The addition of moving parts within the drive increases the risk of generating contaminants. Moreover, these solutions provide latching even when it not required, such as when the drive is not being transported and not subject to vibration (e.g., the drive is merely non-operational). Thus, an improved disk drive design is needed to immobilize the unrestrained components when the drive is not in operation.
A disk drive has a base containing disks that are mounted on a central drive hub. A cover is mounted and sealed to the base. The cover has an aperture that is sealed with a flexible membrane. The membrane is selectively deflected into contact with the hub or one of the disks by a displacement device. The displacement device is completely external to the sealed drive to avoid contaminating the drive. In one version, a disposable plastic snap clamp is secured to the drive to lock the disks from rotation. A pusher finger on the clamp automatically engages and deflects the membrane into frictional engagement with the disk to immobilize it. The locked position is used during periods of non-operation of the drive. When the drive is operational, the clamp is removed to release the disks for rotation.
Accordingly, it is an object of the present invention to provide an improved disk drive.
It is an additional object of the present invention to provide an improved disk drive having a device for immobilizing the disk spindle.
Still another object of the present invention is to provide a membrane-like locking device for selectively immobilizing the disks and/or spindle in a disk drive device.
The foregoing and other objects and advantages of the present invention will be apparent to those skilled in the art, in view of the following detailed description of the preferred embodiment of the present invention, taken in conjunction with the appended claims and the accompanying drawings.